The Dry Summer of 2012 & Gray Colored Clay

Posted by in Foundations | September 18, 2012

The summer of 2012 seemed to be a relatively dry one in Northeast Ohio.  It resulted in much less grass cutting this summer and even fewer weeds sprouting in my yard.   All in all it seemed to be a good thing.

Weather observations at Hopkins International Airport in Cleveland, Ohio recorded an almost 5 inch deficit of rainfall from April through August.  Every month from April through August had a deficit of rainfall with the exception of July.

Unfortunately, the dry weather has also appeared to affect the moisture content in the local soils.  We have noticed a significant increase in calls about cracking in and the dropping of exterior walls.   The cracking and dropping are usually traced back to a dropping footing.

Since there has been no significant increase in the weight on these footings, “Why are they dropping ‘suddenly?'”  We have found that a lot of the cracking and dropping are a recurrence of previous cracking and dropping, as evidenced by previous patching, worn cracking, and/or repairs that fit the downward movement.   In those cases it is not a “sudden” issue.  It is a recurring or present and progressing issue.

Clay soils, which is what we have a lot of in the areas away from the lake, shrink and swell with moisture variation.   The shrinking and swelling is similar to the shrinking and swelling of a cheap sponge.  The effects of the shrinking and swelling on buildings are usually limited because local footings are commonly set to bear on soils over 36 inches (3 feet) below grade.  At 36 inches the moisture content usually doesn’t change much, except when we have the dry conditions similar to what we have had this past summer.

The increase in the reported and observed cracking and dropping indicates that the supporting soils have been affected by the “drought” of the summer of 2012.  The effects seem to have been more severe where the buildings have been constructed in areas observed have a gray colored clay.  The gray colored clay is more sensitive to changes in moisture content (shrinks and swells more) than the more common brown clay.  I can recall that over the years we have observed these gray clays in Strongsville, Westlake, Middleburg Heights, and Independence.  (That doesn’t mean one shouldn’t live there, those are all fine communities.)

What can be done about it?  Some might suggest watering during the drought around shallow foundations such as porches, garages, patios, walkout basements, etc.  Watering might help, but be careful not to over water and cause wetness and excessive groundwater pressures on nearby the basement walls.  In that case, the cure may be worse that the disease.